proxy_ssl_certificate_cache

The proxy_ssl_certificate_cache directive is used within the NGINX configuration to specify how SSL client certificates are cached when making proxied SSL connections. This directive can significantly enhance performance by avoiding the overhead of repeatedly loading certificates on new connections. The command accepts up to three arguments, which define the size of the cache and a specified timeout for the caching mechanism. The first argument sets the cache size (in bytes), while the second and third optional arguments define timeout parameters for how long certificates should be kept in the cache.

When set, NGINX will store client certificates that have been used for proxying to backend servers. A proper understanding of both the cache size and timeout settings is crucial, as incorrect configurations can either lead to excessive memory usage or frequent cache misses that degrade performance. It is also important to note that the behaviors are context-specific; this directive can be placed in the http, server, or location contexts to provide granular control over caching based on different routing or handling rules.

To establish basic caching, an administrator could define a cache size of 10 MB or more and set an appropriate timeout period depending on the expected usage pattern. It is vital to monitor the effectiveness of caching in production scenarios, as high variability in client connections may warrant adjustments to the specified parameters.